It is known that the mobility and ground-holding abilities of vehicles, both civilian vehicles and military vehicles, depend on the pressure to which their tires are inflated, and that it may be necessary to reduce tire pressure from a normal running pressure, for example when a vehicle needs to cross ground that is sandy, muddy, or the like. The pressure to which the tires are inflated must generally be reduced quickly and also to a well-determined value. For this purpose, proposals have already been made either for systems for adjusting tire pressure under control from a vehicle cabin (which systems are extremely expensive and therefore of limited application), or else for devices that can be operated by hand, as described in French Patent 2 655 703 in the name of the present Assignee, for example. The device described in that document includes a pushbutton for actuating a rod suitable for cooperating with the deflation pin of the valve, which pushbutton is mounted in a sleeve and can be secured thereto by means of a coupling having retractable balls, the sleeve itself being slidably mounted in a case which provides a chamber coaxial with the actuator rod for the deflation pin and which has vent holes pierced through its side wall to discharge the gaseous fluid contained in the enclosure to be deflated. Although the operation of such a device is satisfactory, it is nevertheless still too expensive to be commercially successful, in particular when it is recalled that the civilian or military vehicles to be equipped with the device generally comprise a relatively large number of wheels.
To mitigate this cost drawback, Applicants have investigated the possibility of providing a device which is even simpler that the previously known device, and which like the previous device is hand-operated, and is suitable for obtaining reliable and rapid deflation of vehicle tires under conditions that are quantitatively reproducible.